Dicrotendipes Kieffer

Description

Introduction

Medium sized to large, red coloured often with green marbling, up to 11 mm long. Head capsule evenly golden coloured to brown, sometimes with darker brown gula, mentum and/or postmentum, and pale dorsal mandibular tooth. Surface sometimes with regular polygonal patterning. Occipital margin pale to darkened.

Dorsal Head

Frontal apotome separated from clypeus in all but 1 species, with oval to round (usually) or linear frontal fenestra; anterior margin of frontal apotome often crenulate and sometimes expanded laterally into "wings"; clypeus and 1 labral sclerite, remaining labral area variably fragmented.

Antenna

Antenna with 5 segments, segment 4 often obviously elongate (c 4-6x as long as wide); Lauterborn organs moderately developed, opposite on apex of 2nd segment, with small style. Ring organ in proximal 1/3 of segment 1, seta absent. Blade often extending to near apex of antenna.

Labrum

SI palmate or coarsely plumose; SII simple; SIII simple, short; SIV normally developed. Seta praemandibularis simple. Labral lamellae fine, without indication of median division. Pecten epipharyngis of 5-7, exceptionally 12, robust strong teeth. Premandible with 3 teeth, 2nd and 3rd broad and blunt, with moderate brush.

Mandible

Mandible with pale, dorsal tooth, sometimes with small additional teeth attached basally, strong apical tooth and 3-4 inner teeth. Pecten mandibularis modestly developed, not extending to apical mandibular tooth. Seta subdentalis inserted on ventral surface, somewhat variable in shape (broad to narrow), extending no further than innermost tooth of mandible. Margin often crenulate / rugose, inner margin smooth. Seta interna inserted on dorsal surface, strongly plumose, 4-branched.

Mentum

Mentum with simple, robust, sometimes laterally crenate median tooth, 5-6 pairs of lateral teeth on each side, with 1st sometimes obliquely fused to 2nd, then evenly decreasing in size laterally; lateralmost teeth may be variably to completely fused to form bulging lobe. Ventromental plates separated medially by width of 1-2 lateral teeth, narrow, curved, fan-shaped, with smooth (rarely crenate) anterior margin; striae complete. Setae submenti simple, apically divided only in D. nervosus.

Body

Lateral tubules absent, ventral tubules present in a few species.

Notes

Taxonomic Notes

Dicrotendipes larvae, with one exception, have labral sclerite 1 and 2 separate and an antero median pit or mark on the frontal apotome which otherwise occurs only in Demeijerea, Einfeldia (species group A), Glyptotendipes (species group C), and Kiefferulus (including Nilodorum). The pecten epipharyngis almost always has 5-7 broad teeth whilst in the other named genera many teeth are usually present. A useful character is the antennal segment 4 which is 4-6x as long as broad in Dicrotendipes but is distinctly shorter than this in the other mentioned genera.

Ecological Notes

Larvae of Dicrotendipes inhabit littoral sediments of standing (seldom flowing) waters; exceptionally also found in "Aufwuchs".

Worldwide distribution, from the tropics to temperate zones. About 20 species are known from the Holarctic.

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